Phosphorus pentabromide
| Phosphorus pentabromide | |
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_bromide.jpg) | |
| IUPAC name phosphorus pentabromide | |
| Other names phosphorus(V) bromide | |
| Identifiers | |
| CAS number | 7789-69-7 |
| PubChem | 62678 |
| ChemSpider | 56429  |
| Jmol-3D images | Image 1 |
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| Properties | |
| Molecular formula | PBr5 |
| Molar mass | 430.49 g/mol |
| Appearance | yellow solid |
| Density | 3.61 g/cm3 |
| Melting point | ca. 100 °C (decomposes) |
| Boiling point | 106 °C (decomposes) |
| Solubility in water | decomposes |
(verify) (what is: / ?)Except where noted otherwise, data are given for materials in their standard state (at 25 °C (77 °F), 100 kPa) | |
| Infobox references | |
Phosphorus pentabromide is a reactive, yellow solid of formula PBr5, which has the structure PBr4+ Br− in the solid state but in the vapor phase is completely dissociated to PBr3 and Br2. Rapid cooling of this phase to 15 K leads to formation of the ionic species [PBr4]+[Br3]-.
It can be used in organic chemistry to convert carboxylic acids to acyl bromides. It is highly corrosive and should be handled with care. It decomposes above 100 °C to give phosphorus tribromide and bromine:[1]
Reversing this equilibrium to generate PBr5 by addition of Br2 to PBr3 is difficult in practice because the product is susceptible to further addition to yield PBr7.[2]
References
- ↑ Greenwood, Norman N.; Earnshaw, Alan (1997). Chemistry of the Elements (2nd ed.). Butterworth-Heinemann. ISBN 0080379419.
- ↑ Popov, A. I.; Skelly, N. E. (1954). "Spectrophotometric Study of Phosphorus Pentabromide in Various So1vents". J. Am. Chem. Soc. 76 (15): 3916–3919. doi:10.1021/ja01644a014.
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